SIP implementation is difficult.crying

I also looked at Naver SIP-related open-source projects, and Mobile SIP also opened SipServlet, a basic Java API, at Oracle Homepage, but I don't understand it clearly. Of course, I think it is impossible to develop it without any reason, and I need to use open source that has already been developed, but I don't know how to operate basic SIP, so I don't understand it more.ㅠ<

I think it's hard to burn yourself I'm just trying to do the audio.

Client1 After recording for 2 seconds, transfer to server via HTTP + download client 2 recording file from server and play it / After recording for 2 seconds, transfer to server via HTTP + download client 2 recording file from server and play it / After recording for 2 seconds, transfer to server via HTTP + download client 2 recording file from server and play it / ...

Client2 After recording for 2 seconds, transfer to server via HTTP + download client 1 off recording file from server and play it / After recording for 2 seconds, transfer to server via HTTP + download client 1 off recording file from server and play it / After recording for 2 seconds, transfer to server via HTTP + download client 1 off recording file from server and play it / ... Can't we just implement it like this? I feel stuffy